The experimental work proposed is designed to investigate various aspects of metabolic behavior of normal and pathologic articular and epiphyseal cartilage by histologic, ultrastructural, histochemical, autoradiographic, biochemical and metabolic (radioisotopic) techniques. Experiments will be performed to: assess metabolic heterogeneity of the articular chondrocytes in normal and osteoarthritic cartilage; define differential rates of diffusion of isotopic substrates in normal and pathologic articular cartilage and the effect of cell viability on the system; analyze the content of degradative enzymes in articular cartilage from normal and osteoarthritic joints, with special emphasis on collagenase; define the role of uridine diphosphate as a stimulant of proteoglycan synthesis in normal, lacerated and experimentally arthritic articular tissues cartilage; assess the differential rates of synthesis of the glycosaminoglycans in normal, osteoarthritic and lacerated cartilage; determine the optimal technique to produce a biologically valid and reproducible osteoarthritic lesion in the knee joint of the New Zealand white rabbit; analyze the roles of synthesis and degradation of the collagen of cartilage by radioisotopic techniques; and further evaluate the water binding characteristics of the matrix of articular cartilage in vivo and in vitro.